Electrical calculating machine



Feb. 12, 1946. H. P. LUHN 2,394,925

r I ELECTRICAL CALCULATING MACHINE Filed Aug. 28, 1943 5 Sheets-Sheet 1FIGZ I 51 5 mVENToR HANS Ll/H/V BY IS Feb. 12,- 1946. H. P. LUHNELECTRICAL CALCULATING MACHINE Filed Aug. 28, 1943 5 Sheets-Sheet 2lNVENTOR HA/vs r LUHN Af'TORNEY Feb. 12, 1946. H. P. LUHN 2,394,925

ELECTRICAL CALCULATING MACHINE Filed Aug. 28, 1943 5 Sheets-Sheet 3 FIG.'5.

INVENTOR 25% 54mm: hh vs P AaH/v ATTORN EY I Feb. 12, 1946.

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H. P. LUHN ELECTRICAL CALCULATING MACHINE FiledAug. 28, 1943 5Sheets-Sheet 4 UNI T6 OPERA 7E (LEAR TENS Hl/NDREDS T HOUSA NOS INVENTORHANS P LUHN ATTORNEY Feb. 12, 1946; R LUHN 2,394,925

ELECTRICAL CALCULATING MACHINE Filed Aug. 28, 1943 5 Sheets- Sheet 5 NONCARRY 1 INVENTOR 1 HA/vs R LUH/V.

ATTORNEY Patented Feb. 12, 1946 ELECTRICAL CALCULATING MACHINE Hans P.Luhn, Armonk, N. Y., assignor to International Business MachinesCorporation, New York, N. Y., a corporation of New York ApplicationAugust 28, 1943, Serial No. 500,325

6 Claims. ((1235-61) The present invention relates to accountingmachines and more particularly to the data accumulating mechanismthereof.

The principal object of the present invention is to provide a novelaccumulator of the electrical relay type, in which the arrangement ofrelay magnets and contacts is considerably improved and simplified overprior devices.

Another object of the invention is to provide a relay accumulator inwhich all denominational orders are of like construction andarrangement, and in which the orders are connectable in series toprovide an accumulator of any desired denominational capacity.

A further object is to provide novel carry determining mechanism for a.relay accumulator operable for both adding and subtracting operations.

In carrying out the objects of the invention, there is provided in eachorder a set of two-position relay magnets and associated contacts and aset of contacts settable to represent an amount to be entered, and foreach order there are provided two so-called adding chain sets ofconnections. Through one chain the relays are operated in accordancewith the algebraic sum of two amounts without carries, and through theother chain the relays are operated in accordance with the algebraic sumof two amounts with carries. The setting of parts of both sets ofcontacts determines what chain is to be effective by connecting theappropriate chain of each order to the source of current from which asingle impulse passing through all orders will operate the relays inaccordance with the algebraic sum of the two amounts.

A novel arrangement is provided whereby the highest order determiningmeans selects the adding chain of the lowest order, whereby whensubtracting operations are performed in accordance with the method ofcomplementary addition the so-called elusive one is applied to thelowest order, whenever the highest order passes through zero.

A further object is to provide a novel indicating means for displayingat all times the true value of the amount entered into the relayaccumulator together with its algebraic sign.

Other objects of the invention will be pointed out in the followingdescription and claims and illustrated in the accompanying drawings,which disclose, by way of example, the principle of the invention andthe best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 is a detail showing the construction of the amount entering keys.

Fig. 2 is a detail of one of the accumulating relay magnets in its unsetposition.

Fig.- 3 is a detail of one of the accumulating relay magnets in its setposition.

Fig. 4 is a diagram showing certain circuits in simplified form.

Fig. 5 is a view showing the elements included in one denominationalorder of the accumulating mechanism.

Fig. 6 is a diagram showing how four denominational orders of anaccumulator are arranged by repeating the elements in Fig. 4 andinterconnecting them as indicated.

Fig. '7 is a partial diagram of a modified circuit arrangement.

In carrying out the objects of the invention, each denominational orderof the accumulating mechanism comprises four so-called accumulatingrelay devices, each of which has a value assigned thereto in accordancewith the first four terms of the binary progression, namely, 1, 2, 4 and8. unset position with an entry in any one thereof being represented byits set condition. Accordingly, any of the digits from 0 to 9 can be Therelays each have a set and an represented by the setting of one or moreof the relays.

which also have the values of the binary pro- 1 gression assignedthereto.

These latter relays are energized in combinational manner to represent adigit to be entered and for each order such digit may also be from 0 to9.

In the operation of the devices, with the accumulating relays of adenominational order set to represent a digit, another digit to beentered is set on the entering relays. Both kinds of relays consequentlyeffect the adjustment of a system of contacts or switches, soelectrically interconnected that a continuous circuit is establishedwhich causes the accumulating relays to assume a setting representingthe units digit of the sum or difference of the two combined digits.

Amounts to be subtracted are set up on the entering relays in the formof 9's complements and, where the balance is negative, the accumulatingrelays will receive a setting representing the complement of thebalance. The contacts controlled by the relays are so interconnectedthat tens carry requirements are recognized and proper entries effectedfrom order to order.

For each accumulator order there is provided a series of numeralrepresenting lamps constituting a readout device. Through contactsadjustably set by the accumulating relays in an order, the lampcorresponding to the value standing in the order is illuminated toindicate the true value of the amount set on the relays. A pair of plusand minus sign indicating lamps is also provided to indicate thealgebraic sign of the indicated amount.

Before describing the circuits, a brief descrip tion will be given ofthe keyboard construction and of the accumulating relays.

Keyboard In Fig. 1 is shown a portion of the keyboard and a row of keysdesignated I, of which there is one for each of the digits, and a row isprovided for each denominational order to be handled by the machine. Thekeys are suitably mounted for vertical reciprocation in a frameworkgenerally designated 2, in which there is a series of horizontallyslidable latching bars 3, one for each column of keys. Each key I isprovided with-a locking pin 4 which, when the key is depressed, rocksthe related bar 3 toward the left to release any previously latched key.Upon such depression, the bar 3 under the influence of its spring 5snaps back over the pin 4 of the depressed key. Each of the digit keys Iis provided with a set or sets of contacts, generally designated a inFig. 1, with one of the blades curved and inclined as indicated at B forcooperation with a stud or roller 1 on the key stem I. The portion 6acts as a return spring for the key set so that, when released, thepressure of the spring 6 against stud I will elevate the key to itsnormal position.

The several contacts associated with the keys are shown diagrammaticallyin Fig. 5 where the complete set of keys for one order is shown.Directly beneath each key are the contacts (1, arranged to convert thedigit into a coded equivalent directly or in the form of a 9scomplement. The circuits involved will be more specifically pointed outin connection with the description of the circuit diagram.

Accumulating relay One of the accumulating relays is shown in Fig. 2where the parts are shown in normal or unset position. This relaycomprises a magnet generally designated A mounted on the frame I4 towhich there is pivoted an armature 8 at the point 9 and a bell cranklever II] at the point II. Energization of the magnet A will rockarmature 8 counterclockwise against the tension of spring I12. Thisaction will draw lever I3 to the left so that a spring I! will rock thelever about its pivot 23 on armature B to the dotted line position shownin Fig. 2. Pivoted to extension Ma of the frame I4 is a T-shaped leverI5 which is rotatable on the pin I6. The spring I! is connected betweenthe extremity of lever I5 and a pin III on the lever I3 and serves toengage hook 20 of lever I5 to hold it in the position shown in Fig. 2,where a pin 22 bears against the upper end of bell crank l0, holding itin the clockwise position shown, so that its other arm holds the bladesof contacts a, b and c in the relative positions indicated.

When magnet A is energized and lever I3 rocked to its dotted lineposition, the lever I3 is brought into engagement with the upper hook 2|of lever I5 and the spring I! holds the parts in this position as longas magnet A remains energized. Upon deenergization of the magnet, itsspring I2 will return armature 8 and at the same time will rock leversI3 and I5 to the position shown in Fig. 3, in which position the springII will now hold the parts until magnet A is again energized. In thisposition the pin 22 and a second pin 24 have moved to ermit the bellcrank lever II] to rock counterclockwise and enable the contactsassociated therewith to take an alternate position as shown.

position.

When magnet A is again energized, the lever I3 will swing back intoengagement with the hook 2B and upon deenergization of the magnet thearmature I2 will force lever I3 against the hook 20 and the pin 22 willrock the bell crank I 0 clockwise back to the position of Fig. 2. Inthis position it may be noted the pin 24 serves to lock the bell crankI0 against counterclockwise movement.

For each denominational order of the mechanism there are four relayssuch as shown in Fig. 2, each controlling a plurality of contacts whichare specifically designated in the circuit diagram (Fig. 5) where theirpurpose will be explained. In Fig. 5 the four relay magnets areseparately designated as AI, A2, A4 and A3 and the contacts controlledthereby are shown to the right thereof designated by lower case letters.

It is to be borne in mind in following the subsequent explanation thatthe actual shifting of the contacts occurs upon deenergization of themagnet and that upon energization the shifting levers merely move intoposition to prepare for the actual shifting of the contacts.

Operating keg s In Fig. 6 are represented plus and minus sign keysdesignated 25, of which the key 25 shifts contacts a and these are thenlatched by a bar 3. The key simply functions to release contacts a ifthey have been previously shifted and latched. When an amount is to besubtracted the key 25 is depressed and, when an amount is to be added,the key 25 is depressed, although it is apparent that such latter keyneed not be operated unless the key is in its down position.

An operating key 26 and a clearing key 21 are also provided which closecontacts a thereof only while the keys are held depressed, and whichcontacts open of their own resiliency when the keys are released.

Circuit diagram Referring now to Fig. 5, there are represented thedevices for one denominational order of the mechanism with the wiringhaving sets of plug connection sockets designated 23, 29, 30 and 3I bymeans of which several orders may be coupled through connectionsgenerally designated 32 in Fig. 6 to form an accumulator. In the lowestorder, connections are made to the contacts of keys 26 and 2? and, inthe highest order, connections are made to the contacts of the minus key25 and to a pair of sign indicating lamps 33.

Current for the device is supplied through negative line 34 to one ofthe sockets 28 of the units order and through positive line 35 to one ofthe sockets 29 of the same order.

In the circuit diagram (Fig. 5) are represented the four accumulatingrelay magnets Al, A2, A4 and A8 for an order, and the contactscontrolled by the magnets are designated a, b, c, d, e, etc. In thetracing of circuits through these contacts they will be designated bythe reference character of the magnet followed by the letter of theparticular contacts and also followed by the letter L or R to indicatewhether the movable blade of the contact is in its left hand or righthand Thus, for example, the designation A8bR denotes the 2) contacts ofthe A8 relay magnet in its right hand position. This system ofidentification of the contacts is utilized to sim plify the applicationof reference characters to the numerous contacts appearing in thedrawings.

For each denominational order there is also provided a set of four relaymagnets designated RI, R2, R4 and R8, with each of which is associated aseries of contacts designated by lower case letters and which will besimilarly identified as, for example, RBaR or RB-aL as the case may be.These relay magnets are of the type which shift their contacts uponenergization and enable the contacts to return to the normal positionsshown upon deenergization.

For each denominational order there is provided a set of digitrepresenting lamps generally designated 36, and for the entire apparatusthere are provided the two lamps 33 (Fig. 6) which indicate whether theamount standing in the accumulating relays is negative or positive.

In each order of the accumulator the four magnets Al, A2, A4, and A8 maybe considered as having a set or an unset position or condition. Thesemagnets by their condition represent in combinational manner the tendigits. The particular combination for the form illustrated is that ofthe binary system of notation, and for this reason the magnets aredesignated with the numerals 1, 2, 4 and 8 to indicate the terms of thebinary progression with which the magnets are in correspondence. Thus,the digit 1 is represented on the magnets by the setting of magnet Al,the digit 2 by the magnet A2, th digit 3 by magnets AI and A2, etc.

Entering an amount additively To enter an amount, keys I are depressedand latched in accordance with the value to be entered. Assuming thatthe amount 96 is to be entered, the 6 key I of the units order and the 9key I of the tens order are depressed and their a contacts areaccordingly closed. As a result, the R2 and R4 relay magnets of theunits order and the RI and R8 relay magnets of the tens order willbecome energized in accordance with the code combinations for the digits6 and 9, respectively.

The circuits involved are as follows. Referring to Figs. 5 and 6,negative line 34 extends across all orders to the upper contacts a of thkey 25 and continues back through wire 38, so that line 34 and wire 38are electrically connected. For the unit order, current fiows from line34, through wire 39 (Fig. 5), the a contacts of the 6 key I lying alongthe horizontal line designated 2, the 2 wire 40, relay R2, to positiveline 35. Concurrently, current flows from wire 38, wire 4!, branch wire42, a contacts of the 6 key in the 4 position, the 4 wire 40, relay R4to line 35.

In the tens order, the circuit for relay RI is traceable from wire 38,wire M, the a contacts of the 9 key in the 1 position, the 1 wire 40 andrelay RI to line 35. The circuit for relay R8 is traceable from wire 38,wire 4 I, a branch wire 43, the a contacts of the 9 key in the 8position, the 8 wire 40, relay R8 to line 35.

Inspection of the upper part of Fig. 5 will show that for each of theother digits the R relays will be energized in accordance with thebinary combination through either wire 39 or 4|.

Entering an amount subtractioely When an amount is to be subtractivelyentered, the key 25 (Fig. 6) is depressed and latched prior to operationof keys I. This results in opening the upper a contacts of key 25 andclosing the lower a contacts to electrically connect line 34 with wire44 which extends back through all the orders. Assuming the same amount96 is to be subtractively entered, the circuits for the 6 key in theunits order are traceable on Fig. 5 as follows: from line 34, 'wire39,11 contacts of the 6 key in the 2 position, 2 wire 40, relay R2 toline 35. Concurrently, there is a circuit from negative wire 44, wire45, a contacts of the 6 key in the 1 position, 1 wire 40, relay RI toline 35.

For the 9 key in the tens order there will be no circuits completed,since both its contacts are connected to the wire 38 which is nowdisconnected from line 34. Inspection of Fig. 5 will show that for eachof the other digits the R relays will be energized in accordance withthe binary combination of the 9s complement of the digit through eitherwire 39 or 45.

Adding a digit in the units order-without carry Since the presentmechanism is to perform subtractive operations, consideration must behad for the so-called elusive or fugitive one, and in the present caseprovision is made to control the adding in the units order through thehighest, or in the instant example, the thousands order. The circuitsare so designed that this control through the highest order is alsoeffected during adding of positive amounts in the novel manner, whichwill be clearer by taking the specific example of entering a 6 in theunits order. Under such assumption the magnets R2 and R4 in the unitsorder are energized under control of the 6 key of the units order asexplained. The RI and R8 magnets of this order and all R magnets inhigher orders are deenergized. The A magnets in all orders are in theirunset position, that is, their contacts are in the positions shown inFig. 5.

Closure of the a contacts of key 26 (Fig. 6) connects negative line 34through wire 46 to a wire 41 extending across all accumulator orders,and under the conditions assumed a circuit can be traced from line 34,contacts of key 26, wire 43, wire 41 (Fig, 5 considered now as thethousands order), a wire 53, contacts A47'R, R4kR, R8hR, ABiR, wire 49,connection to a wire 54 (Fig. 6), connection to wire 55 extending backacross all orders to wire 56 which is connected to wire 58 in the unitsorder (see Fig. 5). From wire 58 (considering Fig. 5 as the units order)the circuit continues through a wire 5I, the right handmost of six oneway current flow devices 52 in the form of rectifiers, contacts RIhR,RZIL, R4gL, A8gR, A4 R, AZeR, CLaD (representing the 11 contacts of arelay CL in down position), magnet A2, to positive line 35.

A parallel circuit is traceable from wire 50, through wire 5I, thefourth rectifier 52 from the left, contacts RIJR, RZdL, R4dL, ABJR,CLbD, magnet A4 to positive line 35. Thus, the magnets A2 and A4 in theunits order are energized and when the contacts of operating key 26reopen, the mechanism associated with these magnets will shift therelated contacts to their set positions.

Briefly, it may be stated that when the highest order of the accumulatorcontains no entry or, as may be seen from inspection, any entry otherthan 9, the energizing circuit for the units order is directed throughthe wires 55 and 56 to the wire 50 of the units order. To show that thisis so, assume that the thousands order contains an 8, evidenced by theA8 magnet in that order being in its set position. Then the circuit runsfrom negative wire 41', wire 53, contacts'RIjR, AI R, RZQR, AZgR, A4hR,R47'R, R8gR, A8zL, wire 49, wire 54 (Fig. 6) to wire 55, and thencethrough the units order wire 50 as before.

It may, therefore, be generally stated that the summation circuitthrough the lowest or units order is completed through wire 5!] and thecarry determining set of contacts of the highest or thousands order.Obviously, if subtracting operations were not involved and the highestorder chosen were far enough to the left so that no significant entrieswill be made therein during a succession of additive entries, suchhighest order will always remain at a setting and the summation circuitfor the units order will always follow the path traced from negativeWire 34, through the carry determining contacts of the thousands order,to wire 59 in the units order and its noncarry wire From here thecircuits will vary according to the digits to be added and will resultin setting the A magnets to represent the units digit of the sum of thetwo digits.

It will be explained later under Subtraction that when an amount issubtractively entered (by adding the 9s complement thereof), the sum maychange from a negative value represented by a complemental setting ofthe accumulator, to a positive setting. In such case the highest orderwill alter its control of the summation circuit for the lowest order tointroduce the socalled elusive or fugitive one into such summation toincrease it by one unit.

Entering a digit in the units order-with carry Consider now the additionof an 8 to the 6 already entered. Then, at the time the operating key 29is depressed the relays will be conditioned as follows:

Amount Thousands Hundreds Tens Units 0 A2A4 s RS which is to result inUpon depression of key 26, a circuit is traceable from negative wire ll(Fig. 5 as units order), wire 53 carry determining contacts A ikL, RlmR, RBy'L, A87'R, wire El, to wire 59 in the tens order in which thecircuit extends, through a branch (Fig. 5 as tens order), contacts RlbR,CLdD, magnet Al to positive line 35. This will cause entry of a unit inthe tens order, this unit being the result of a tens carry from theunits order, where 6 and 8 are added.

The circuit through the units order magnets is controlled through thethousands order contacts as before with the circuit being traceable fromnegative wire ll (thousands order), wire 53, contacts AMR, R lkR, RShR,ASZ'R, wire 99, wire 59, wire 55 (units order), wire 59 to wire 59, wire5i, rectifier E52 farthest to the right, contacts RlhR, RZ R, RMR,RileL, AZeL, CLaD, magnet A2 to line 35. As a result, when key isreleased, the contacts of magnet A2 shift back to their unset position,leaving only magnet set in the units order, and in the tens order thecontacts of magnet Al become set.

Analyzing the conditions thus far considered, it will be observed thatin the units order the wire 53 extends to sets of contacts arranged atits left and right which determine whether the sum of the two digits tobe added in that order is less than or more than 9. If less than 9, theydirect the circuit to so-called non-carry wires 39, 59 as traced for theinitial entry of 6 (6+0 being less than 9). If more than 9, they directthe circuit to so-called carry wires 51, 58 as traced for the entry of 8(6+8 being more than 9). Stated in another way, for the tens and eachhigher order the impulse from negative side of line enters through wire53 and branches through the carry determining contacts to non-carry wire49 if the sum of the digits to be added in the order is less than 9, andto the carry wire 51 if the sum is more than 9. In the next higher orderthen, this impulse Will continue through wires 5| or 59 if a non-carryor carry is indicated respectively to continue through one part oranother of the set of summation contacts to adjust the A relaysaccordingly, The summation contacts through which the impulse from thenon-carry wire 5i passes are interconnected in accordance with the tableof addition, and the contacts through which the impulse from the carrywire 59 passes are interconnected in accordance with the table ofaddition plus a unit, so the ultimate setting of the A relays is oneunit higher than the units digit of the sum of the two digits added inan order.

As already explained for the units order, when adding only is beingperformed, there will be no carry into the units order but the impulseto the non-carry wires 59 and 55 of this order passes through thehighest order.

In the special case where the units digit of the sum of two digits to beadded in an order is 9 or the order initially stands at 9, an impulseentering such order through carry wires 58, 59 will go through thelatter to add a unit in that order and will also branch through thecarry determining contacts to the carry wire 5? to the next higherorder, to also add a unit therein. This is the socalled carry-on-carry.Inspection of the circuit connections through the set of C contacts(Fig. 5) will disclose that, whenever relays A or R are set to represent9, or both are set to represent a total of 9, no circuit can becompleted through these C contacts from wires 4?, 53. When subtractingis performed and a complement stands in the accumulator so that thehighest order (thousands) stands at 9 and a positive amount is to beentered, which will change the accumulator setting to a positivequantity, there will be a carry into such highest order from its carrywire 58, through the carry determining contacts (set at 9) to its carrywire 5? (see Fig. 6), and thence through wires 6t, 62, 93 to the carrywire 58 in the units order, from which the branch 59 continues thecircuit through the summation contacts in the units order to add a unitto the sum of the digits added in that order.

To make the understanding of the circuit con nections clearer, Fig. 4illustrates connections to the negative wire All with the sets of carrydetermining contacts represented as switches C and D, each having threepositions over, under, and 9. When the sum of the two digits in an orderis over 9, switches C and D are in their over position, when the sum isless than 9, they are in their under position, and when the sum is equalto 9, they are in their 9 position. In Fig. 4 switch arm 0 representsthe set of carry determining contacts designated C in Fig. 5, andindicates that when the sum of two digits in an order is under 9, thesecontacts form a closed connection from negative wire 53 to the non-carrywire 49 extending to the corresponding wire 59 in the next higher order;that when the sum is over 9, there is no circuit through these contacts;and that when the sum is 9, the contacts connect the non-carry wire 50to the non-carry wire 49 and non-carry wire 59 in the higher order.Switch arm D represents the set of carry determining contacts designatedD in Fig. 5, and indicates that when the sum of two digits in an orderis under 9, they complete no circuit; that when the sum is over 9 theyconnect the negative wire 53 to the carry wire 5! to send a unit to thenext higher order; and that when the sum is 9, they connect the carrywire 58 to such carry wire 51. Thus, the contacts represented byswitches C and D provide for all conditions of carry and carrycn-carrybetween orders, with the special provi sion of a carry into the unitsorder from the highest order when the latter is to change its settingfrom 9 to 0.

The circuits take care of a special condition wherein, as the result ofthe addition of a positive amount added to a complement standing in theaccumulator, the result will be in all orders. Thus, for example, if thecomplement is 9997 and a 2 is added, the resultant setting will be 9999.Under such circumstances all switches C and D will be in their 9positions and no circuit will be completed to negative source throughwire 41. For this reason a set of zero balance contacts designated E inFig. 5 and represented by switch E in Fig. 4 are provided which, when a9 condition is set in all orders, will complete a series circuit asclear from Fig. 4, running from negative wire 41, through all switches Eto the noncarry wire 49 in the highest order, and thence through wires54, 55 and 56 to the non-carry wire 50 in the units order to change itssetting from 7 to 9.

Considering the previously traced operations again but with respect toFig. 4, with the A magnets all unset and the R magnets in the unitsorder energized to add 6, switches C and D in all orders will be asshown in Fig. 4 and the circuit from negative wire 41 extends throughunits wire 53, switch C, wires 49, 50 to the tens non-carry wires 5|.Concurrently, a circuit from negative wire 41' extends through thousandswire 53. switch C, wires 49, 54, 55, 56 and 50 to the units noncarrywire 5|.

For the second operation where 8 is added to 6, switches C and D in theunits order are in their over positions and all others are in the underpositions, and the circuit from negative wire 41 extends through unitswire 53, switch D, to carry wires 51, 58 in the tens order.Concurrently, the circuit from negative wire 41 extends throughthousands wire 53, switch C, wires 49, 54, 55, 56 and 50 to the unitsnon-carry wire 5|.

Considering now the example of 25 added to 14, the circuits involvedwill be traced in connection with both Figs. 4 and 5. Upon depression ofthe entering keys, the magnet contacts will be set as In the units orderswitches C and D will be in their 9 positions and in all other ordersthey will be in their under positions. Upon depression of key 2 6, acircuit is traceable from negative wire 41, wire 53, in the thousandsorder, switch C (representing contacts A47R, R4kR, R8hR, ABiR, wire 49),wires 54, 55, 56 to noncarry wire 50 in the units order, thence throughwire 5|, rectifier 52, second from the left, contacts RlcZL, AlcR, RZbR,R4bL, A4bL, AZbR, CLcD, magnet A8 to line 35.

A parallel circuit extends from wire 5|, rectifier 52, fourth from theleft, contacts RIJL, AldR, RZdR, RAIL, A4eL, CLbD, magnet A4 to line 35.

A third parallel circuit extends from wire 5|, contacts RIbL, CLdD,magnet A| to line 35. When key 26 is released, the contacts of magnet A4will become unset and the contacts of magnets Al and A8 will become set.

A still further circuit extends from units wire 50, through switch C(Fig. 4) or in Fig. 5, contacts RljL, AIfR, R2gR, AZgG, A4iL, R4kL,RBhR, ASiR, non-carry wires 49, 50 to the tens order. In this order thecircuit extends through wire 5|, rectifier 52, farthest to the right,contacts RlhR, RZ L, R4gR, RSfR, A8hR, CLaD, magnet A2 to line 35. Whenkey 26 is released, the contacts of magnet A2 become set so that thedigit 3 is now entered in the tens order and a 9 stands in the unitsorder.

In Fig. 5 the four branch circuit connections extending upwardly fromthe non-carry wire 5| continue through separate paths to each controlone of the magnets Al, A2, A4 or A8, through the contacts of thesummation set which are wired in accordance with the table of additionfor binary representations. Through these four connections the A magnetsin each order will have their settings changed to represent the unitsdigit of the sum of the two digit initially set on the A and R magnetsof the order, and the contacts and connections involved may be termed anon-carry adding relay chain.

In a like manner the four circuit connections extending upwardly fromthe carry wire 59 continue through separate paths to each control one ofthe magnets Al to A8 to change their settings to represent one unithigher than the units digit of the sum of the two digits initially seton the A and R magnets of the order. In other Words, the determiningcontact chains represented by switches C and D of Fig. 4 select eitherthe noncarry adding chain or the carry adding chain for operation in thenext higher order. It is to be particularly noted that, when the Rrelays have been set to represent the amount to be added, the momentaryclosure of the contacts or key 26 will concurrently complete all thenecessary circuits to adjust the A relays in accordance with the total.

Carry-on-carry example The circuits involved in an example where theso-called. carry-on-carry conditions exist will be traced for a betterunderstanding of the arrangement. Considering the example of 62 added to39, upon depression of the entering key the magnet contacts will be setas follows:

Amount Thousands Hundreds Tens Units 23 Peta: 3. 51 1 which is to resultin Referring to Fig. 4, the switches C and D in the units order will bein their over positions. In the tens order they will be in their 9positions, and in the higher orders they will be in their underpositions. When the operating key contacts are closed, a circuit istraceable from negative Wire 41, unit wire 53, switch D to carry wires51, 58 (or in Fig. contacts RZz'L, AZiR, A4kR, R4mR, RBiR, A891, wires51, 5S), tens wire 59, contacts RlbR, CLcZD, relay A| to line 35. Thusrelay AI will become unset.

A parallel circuit extends from tens wire 59, rectifier 52, fifth fromthe left, contacts RlgR, AleL, RZeL, R4hL, A2eL, CLaD, magnet A2 (tounset the same), and to line 35. Thus, the tens order will represent 0.

A further parallel circuit extends from the tens wire 58, through switchD (Fig. 4) in the 9 position to carry wires 51, 58 extending to thehundreds order, or in Fig. 5 from tens wire 58, contacts RIkR, AlgL,RML, A27'L, A4mR, R4nL, R87R, A87'R, carry wires 51, 58 to the hundredsorder where the circuit continues through wire 59, contacts RIbR, CLdD,magnet Al to line 35, to thereby enter a 1 in the hundreds order.

For the units order the circuit is traceable in the same manner aspreviously explained from negative wire 41, the thousands wir 53 (Fig.4), switch C, and then through wires 49, 54, 55, 56 to the units ordernon-carry wire 50, from whence it branches through the adding network toenergize magnet A8, leaving magnet A| alone in set condition and thereis then set, upon release of the operating key, the sum 101.

Subtraction As already explained, subtraction is effected by depressingthe entering keys in accordance with the amount to be subtracted whichincludes depressing the 0 keys in orders to the left of the highestsignificant position, and depressing the key 25. This results inenergizing the R relay magnets in accordance with the 9s complement ofthe amount to be subtracted and from such point the operation is one ofaddition. Considering the example of 84 subtracted from 101, upondepression of the entering keys the magnet (set at over), carry wires51, 58 to the thousands order where the circuit branches through switchD (set at 9) to carry wire 51, a connection Si, wire 62 (see also Fig.6) connection 53 to the carry Wire 58 in the units order, from which itbranches through the adding chains to energize magnets A2 and A4 toeifect a setting of '7 therein. Thus, through this circuit the so-calledfugitive or elusive one is entered in the units order to produce thecorrect total.

Inspection will thus show that whenever the highest order R magnets areset to represent 9 and the total is to result in a positive amount, thesetting of the units order is through its carry wire 58.

Considering now the example of 19 subtracted from 17, upon depression ofthe entering keys the magnet contacts will be set as follows:

Amount Thousands Hundreds Tens Units t; RI E; 55 1s L-IR; 5

which is to result in -2 A1A8 Al-A8 Al--A8 AlA2A4- This negative resultwill be set on the A magnets as a 9s complement and with reference toFig. 4 the switches C and D of the units order will be at under, theswitches C and D of the tens order will be at 9, the switches C and D ofthe hundreds order will be at 9, and the switches C and D of thethousands order will be at 9. Adding will take place as though the twopositive amounts 17 and 9980 were added to obtain 9997 with adding inthe units order being through the non-carry wire 50. Such addingcircuits will be apparent from the foregoing examples, so the same willnot be repeated.

As a further example, consider the subtraction of 590 from 340. Upondepression of the enter ing keys, the magnet contacts will be set asfollows:

001158.055 Will be set as IOHOWSZ Amount Thousands Hundreds Tens UnitsAmount Thousands Hundreds Tens Units 340 A1A2 A4 -sn0 Rl-R8 R RlR8 +101Al- A1- 84 R1 R3 R1 R8 R1 R1 R4 which is to result in which is to resultin 250 Al A8 AlA2A4 A4 Al A8 A A In the units order switches C and DWill be set The circuits involved in this subtraction may be brieflyexplained in connection with Fig. 4, wherein the switches C and D forthe units and tens positions Will be set at under, the switches C and Dfor the hundreds order will be set at over, and the switches for thethousands order will be set at 9. Upon closure of the operating keycontacts, current flows from negative wire 41, units wire 53, switch C,non-carry wires 49, 59 to the tens order wherein a single circuit iscompleted to energize magnet Al for setting of its contacts.

A parallel circuit runs from wire 41, tens wire 53, switch C, non-carrywires 49, 50 to the hundreds order wherein also a single circuit is completed to energize the magnet Al for unsetting of its contacts. Afurther circuit extends from wire 41, through the hundreds wire 53,switch D at 9. in the tens order switches C and D will be set at under,in the hundreds order switches C and D will be set at under, and in thethousands order switches C and D will be set at 9. Adding will takeplace as though the two positive amounts 340 and 9409 were added toobtain 9749. In this example, no carries are required and the summationcircuits for each order are traceable in Fig. 4 as follows: For thehundreds order, from negative wire 41, wire 53 in the tens order. switchC (tens) in its under position, to noncarry wire 5| of the hundredsorder. For the thousands order, from negative Wire 41, wire 53 in thehundreds order, switch C (hundreds) in its under position, to non-carrywire 5| of the thousands order. For the units order, branches fromnon-carry wire 5| of the thousands order, switch C (thousands) in its 9position, wire 49, 54, 55 and 56 to the non-carry wire 5| in the unitsorder. For the tens order, branches from the non-carry wire 5| of theunits order, switch C (units) in its 9 position to the non-carry wire 5|of the tens order. Thus, in all orders the noncarry Wire 5| conducts theimpulse through the summation chain of contacts.

Assuming now a still further example of subtracting 590 from a negative340 standing in the accumulator as 9659, its 9s complement. Upondepression of the entering keys the magnet contacts will be set asfollows:

Amount Thousands Hundreds 'lens Units 1333 3 grist: skit; 111? which isto result in +250 A2- Al-A4- In the units order switches C and D will beset at 9, in the tens order switches C and D will be set at over, in thehundreds order switches C and D will be set at over, and in thethousands order switches C and D will be set at 9. Adding will takeplace as though the two positive amounts 9659 and 590 were added toproduce 0249, which however requires a fugitive one correction toproduce the correct result 0250.

The summation circuits for each order will be as follows: for thehundreds order, from negative wire 41, wire 53 in the tens order, switchD (tens) in its over position, to carry wire 59 of the hundreds order.For the thousands order, from negative wire 41, wire 53 in the hundredsorder, switch D (hundreds) in its over position, to carry wire 59 in thethousands order. For the units position, branches from carry wire 59 ofthe thousands order, switch D (thousands) in its 9 position, Wires 51,6|, 62, 63, 58 to carry wire 59in the units order to enter the sum of 9and a fugitive 1 in this order. For the tens order the circuit branchesfrom carry wire 59 of the units order, switch D (units) in its 9position, to carry wire 59 of the tens order to enter the sum of 5 and 9and a carried unit in this order.

A special condition arises when an amount is added to a complementstanding on the A magnets which reduces the result to 0. For example,

assume a 2 to be added to the complement 9997. Then upon depression ofthe operating keys the magnet contacts will be set as follows:

Amount Thousands Hundreds V 'lcns Units 2 A1-A8 A1A8 Al-A8 AlA2A4 +2 R2which is to result in Al-A8 Al-A8 1 Il -A8 A lAS Inspection of Fig. 4shows that for this condition all the C and D switches will stand intheir 9 positions and consequently there is no connection to the line41. An additional circuit path is provided which under thesecircumstances is traceable from the units wire 48 (connected to negativewire 41, Fig. 6), through contacts RlnR (Fig. AlhL, RZkL, R40R, A4oL,A'ZkL, Wire 65 to wire 48 of the tens order, contacts RlnR, AlhL, RZkR,R4pR, R8kR, A8kL, A4pR, AIIcR, wire 55 to wire 48 of the hundreds order,through which it continues the same as through the tens order, and thenthrough the thousands wire 48 and the same contacts as in the tens andhundreds orders to the thousands wire 65 which in Fig. 6 is connected bya wire 66 to the non-carry wires 54, and 5G to the units non-carry wire50, through which it goes through the adding chain to energize magnetsA2 and A4 to unset the contacts and magnet A8 to set its contacts. Whenthe operating key is released, all the A! and A8 magnets will have theircontacts in a set condition.

The circuit just traced is represented in 'Fig. 4 where the contactchains between wires 48 and in each order are represented by switches Ehaving an open position and a closed or 9 position.

Sign of total indicating lamps The lamps 33 (Fig. 6) are controlled bythe highest order of the accumulator so that, when this order containsa. 9 indicating a negative total), the lamp 33 is illuminated, and, whenit contains any other digit (indicating a positive total), the lamp 33is illuminated. For this purpose each order is provided with a switch 61which is closed in the highest (thousands) order and a circuit iscompleted as follows: if such highest order is set at a digit other than9, from negative line 34 (Fig. 5) switch 61, contacts AltR, to Wire 68which in Fig. 6 connects through a wire 69 to lamp 33 and positive line35. With a 9 standing in the thousands order the circuit is from line34, switch 61, contacts AltL, AL, to wire 10 which in Fig. 6 connectsthrough a wire 11 to lamp 33 and positive line 35.

The highest order of the accumulator is any order high enough indenomination so that no direct entries are made therein; that is, it isdevoted entirely to sign determination and fugitive one control, so thatno erroneous entry will result.

Total indicating lamps Briefly, then, when the total is positive, wires68 in all orders are connected to negative line 34 and, when the totalis negative, wires 10 in all orders are connected to negative line 34.In each order directly above lamps 36 is a circuit network through whichthe positive value of the total is displayed under control of contactsof the A magnets. A pair of examples will serve to illustrate. Assuminga positive digit of '1 to be standing in an order (represented by asetting of the contacts of magnets Al, A2 and A4), then a circuit willbe traceable from negative line 34, wire 58, contacts AZmL, A4rL, AlkL,'7 lamp 36 to positive line 35. Assuming a negative digit of '7 to bestanding in an order (represented by a set ting of the contacts ofmagnet A2), then a circuit will be traceable from negative line 34, wire19, contacts AZnL, A4tR, AlmR, 7 lamp 315 to positive line 35. Similarcircuits are readily traceable for each of the other digits.

Clearing the accumulator When it is desired to clear the accumulator.key 21 (Fig. 6) is depressed to close its contacts and as a result relaymagnets CL (Fig. 5) become energized through a circuit from line 34,contacts of key 21, wire 12 extending across all the accumulators, themagnets CL in parallel, to line 35. In each order the magnet CL shiftsits contacts a, b, c and d from the down position shown to their upposition and any A magnets, whose contacts are in set position, willhave a pair of a contacts closed to direct an impulse to the magnet toshift the contacts to unset position. Specifically, assuming magnet A2(Fig. 5) to be set with its contacts A2a shifted to the left, then whencontacts CLa shift, a circuit is traceable from line 34, wire '13,contacts AZaL, CLaU, magnet A2 to line 35. Upon release of key 2'! theshift to unset position takes place and the lamps display +0000.

There is thus disclosed an improved relay accumulator in which, after arelay setting of an amount to be entered and its sign have beeneffected, a single momentary impulse will eifect the algebraicsummation. It is to be noted that the entry key settings remain latcheduntil a new setting is effected or all keys are operated. This enablesrepeated entry of the same amount simply by the repeated operation ofkey 26 so that multiplication may readily be performed in accordancewith the method of repeated addition.

Modification Fig. 7 shows a modified arrangement of the adding circuitconnections wherein the addingwith-carry connections are entirelyseparated from the adding-without-carry connections. For thisarrangement the A magnets are provided with two windings as indicatedwith one set of windings controlled through connections and relaycontacts extending from the non-carry wire and the second set extendingfrom the carry wire 59. For comparison, the same reference charactersare used for corresponding contacts in Fig. 5 and inspection will showthat the circuit connections extending through all the contacts down tothe RI contacts are the same. The RI contacts are divided into twoseparate sets, one under the group designated non-carry and the otherunder the group designated carry with the two groups being the sameabove these contacts. In the right hand, or additional control group,the same reference characters as in the first are employed with. a primeand, when comparison is made with Fig. 5, it will be observed that thecircuit arrangement of the latter figure is in effeet the two groups ofcontacts of Fig. 7 merged into one with one way current flow rectifiers52 employed to prevent back circuits, and by this means the carry andnon-carry adding connections traverse common paths for the greaterextent of their paths between wires 5| or 59 and the A magnets.

The circuit of Fig. 5 may be still further simplified by the omission ofthe circuit connections and contacts from contacts A27c down throughBin, if it is determined in advance that a negative 0 will not occur inthe handling of accountin problems, since as explained these contactsare provided to take care of the special case where the sum in allorders is 9.

While there have been shown and described and pointed out thefundamental novel features of the invention as applied to a singlemodifica tion it will be understood that various omissions andsubstitutions and changes in the form and details of the deviceillustrated and in its operation may be made by those skilled in the artwithout departing from the spirit of the invention. It is the intention,therefore, to be limited only as indicated by the scope of the followingclaims.

What is claimed is:

1. In. combination, in a relay accumulator, a group of contact sets, oneset for each denominational order of the accumulator, each set beingadjusted to represent a digit of the amount in the accumulator, aplurality of magnets for each order for adjusting said contacts, asecond group of contact sets, on set for each denominational order ofthe accumulator, each set being adjusted to represent a digit of anamount to be entered into the accumulator, adjusting means therefor, afirst set of circuit connections, for each order, interconnecting afirst part of the contacts and said magnets of the related order inaccordance with the table of addition for the two digits, a second setof circuit con nections, for each order, interconnecting a second partof the contacts and said magnets of the related order in accordance withthe table of addition for the two digits plus a carry digit, a third setof circuit connections, for each order, interconnecting a third part ofthe contacts in accordance with the table of addition for the twodigits, a fourth set of circuit connections, for each order,interconnecting a fourth part of the contacts in accordance with thetable of addition for the two digits, the first and second sets ofconnections of each order being connected in series with the third andfourth sets of connections, respectively, of the next lower order, thfirst and second sets of connections of the lowest order being connectedin series with the third and fourth sets of connections, respectively,of the highest order, a pair of current source lines, said magnets beingconnected to one of said lines, a pair of operating contacts connectedto the other of said lines, and effective when the sum in each order ofthe two digits set therein is under 9, for completing parallel circuitsextending serially through the first sets of connections of each orderand the third sets of connections in series therewith to the other ofsaid source lines to cause the magnets to adjust their contacts torepresent the sum of the two amounts.

2. In combination, in a relay accumulator, a group of contact sets, oneset for ach denominational order of the accumulator, each set beingadjusted to represent a digit of the amount in the accumulator, aplurality of magnets for each order for adjusting said contacts, asecond group of contact sets, one set for each denominational order ofthe accumulator, each set being adjusted to represent a digit of anamount to be entered into th accumulator, adjusting means therefor, afirst set of circuit connections, for each order, interconnecting afirst part of the contacts and said magnets of the related order inaccordance with the table of addition for the two digits, a second setof circuit connections, for each order, interconnecting a second part ofthe contacts and said magnets of the related order in accordance withthe table of addition for the two digits plus a carry digit, a third setof circuit connections, for each order, interconnecting a third part ofthe contacts in accordance with the table of addition for the twodigits, a fourth set of circuit connections, for each order,interconnecting a fourth part of the contacts in accordance with thetable of addition for the two digits, the first and second sets ofconnections of each order being connected in series with the third andfourth sets of connections, respectively, of the next lower order, thefirst and second sets of connections of the lowest order being connectedin series with the third and fourth sets of connections, respectively,of the highest order, a pair of current source lines,

said magnets being connected to one of said lines, a pair of operatingcontacts connected to the other of said lines, and effective when thesum in each order of the two digits set therein is over 9, forcompleting parallel circuits extending serially through the second setsof connections of each order and the fourth sets of connections inseries therewith to the other of said source lines to cause the magnetsto adjust their contacts to represent the sum ofthe two amounts.

3. In combination, in a relay accumulator, a group of contact sets, oneset for each denominational order of the accumulator, each set beingadjusted to represent a digit of the amount in the accumulator, aplurality of magnets for each order for adjusting said contacts, asecond group of contact sets, one set for each denominational order ofthe accumulator, each set being adjusted to represent a digit of anamount to be entered into the accumulator, adjusting means therefor, afirst set of circuit connections, for each order, interconnecting afirst part of the contacts and said magnets of the related order inaccordance with the table of addition for the two digits, a second setof circuit connections, for each order, interconnecting a second part ofthe contacts and said magnets of the related order in accordance withthe table of addition for the two digits plus a carry digit, a third setof circuit connections, for each order, interconnecting a third part ofthe contacts in accordance with the table of addition for the twodigits, a fourth set of circuit connections, for each order,interconnecting a fourth part of the contacts in accordance with thetable of addition for the two digits, the first and second sets ofconnections of each order being connected in series with the third andfourth sets of connections, respectively, of the next lower order, thefirst and second sets of connections of the lowest order being connectedin series with the third and fourth sets of connections, respectively,of

the highest order, a pair of current source lines,

said magnets being connected to one of said lines, a pair of operatingcontacts connected to the other of said lines, and efiective when thesum in a higher order is under 9, the sum in the next lower order is 9,and the sum in the second lower order is over 9, for completing acircuit extending serially through the second set of connections of saidhigher order, the fourth set of connections of the next lower order andthe fourth set of connections of the second lower order to the other ofsaid source lines, and effective for concurrently completing a circuitextending serially through the second set of connections of said nextlower order and the fourth set of connections of the second lower orderto the other of said source lines and effective for concurrentlycompleting a circuit extending serially through the second set ofconnections of said second lower order and the first set of connectionsof a still lower order to the other of said source lines.

4. The invention set forth in claim 1 in which a fifth set of circuitconnections is provided for each order, said sets of connections beingconnected in series and arranged to complete a circuit, when the sum ofthe two digits in each order is 9, connecting the first set ofconnections of the lowest order to the other of said source lines.

5. In a relay accumulator, having contacts settable to represent anamount therein, entering contacts in each order settable to represent anamount or the 9s complement of an amount to be entered, in combinationwith magnets operable to adjust the first named contacts to representany amount, a first group of circuit connections including part of saidcontacts and the magnets arranged and normally effective to cause themagnets to adjust the first named contacts in accordance with the sum ofthe two amounts set on the two sets of contacts, a second group ofcircuit connections including part of said contacts and the magnetsarranged to cause the magnets to adjust the first named contacts inaccordance with the sum of the two amounts +1, and means controlled by apart of the contacts of each order, when the sum of the digits set onthe related contacts is greater than 9, for rendering the first group ofconnections in the next higher order inefiective and rendering. thesecond group of connections effective, the means controlled by said partof the contacts of the highest order being effective when the sum of thedigits therein is greater than 9 for rendering the first group ofconnections related to the lowest order ineffective and rendering thesecond group thereof eflective.

6. An electrical relay accumulator comprising, for each denominationalorder, a plurality of accumulating relays settable to represent a digit,a plurality of entering relays settable to represent a digit to beadded, a first set of contacts adjusted by the accumulating relays, afirst set of contacts adjusted by the entering relays, said sets ofcontacts being interconnected in accordance with the table of addition,to efiect a setting of the accumulating, relays to represent therein theunits digit of the sum of the two digits to be added, a second set ofcontacts adjusted by the accumulating relays, a second set of contactsadjusted by the entering relays, said second sets of contacts beinginterconnected in accordance with the table of addition to effect asetting of the accumulating relays to represent one digit more than theunits digit of the sum of the two digits to be added, means forselectively completing a circuit through either set of contacts, a thirdset of contacts adjusted by the accumulating relays, a third set ofcontacts adjusted by the entering relays, means j i t y controlled bythe said third sets of contacts of each order for determining whetherthe sum of the digits in an order is greater or less than 9, saiddetermining means acting. concurrently for all orders to render theselective completing means of all higher orders concurrently efiectiveto complete a circuit through the first or second sets of contacts ofall such higher orders, and means controlled by the determining means ofthe highest order for rendering the selective completing means of thelowest order effective to complete a circuit through the first or secondnamed sets of contacts.

HANS P. LUHN.

